1. Field of the Invention
The present invention relates to an apparatus for controlling the operation of tipping a melting crucible, having a pouring curve that is stored in a memory, which controls the pouring operation, at least from the beginning of pouring out, when the melting crucible assumes the pour-lip angle .alpha..sub.PL, until the melting crucible has been completely emptied, in accordance with a function .alpha.=f(t) which is referred to certain geometric conditions of the melting crucible and/or of the molten material and in which .alpha. represents the tipping angle of the melting crucible and t represents time.
2. Background Information
In the manufacture of precision cast articles it is necessary for the pouring operation to take place within a very short time in order that all the liquid molten material in the mold be subjected to the solidification process as simultaneously as possible. If pouring is carried out too slowly, the molten material first poured into the mold will alread have cooled and solidified by the time that the molten material poured later reaches the mold. Articles cast in this manner do not meet the desired values from the point of view of strength.
In order to ensure that the molten material is poured out of a crucible and into a mold in a rapid and reproducible manner, the pouring operation must be automatically controlled. The so-called "teach-in" method is particularly advantageous. In this method, for example, various test pouring operations are carried out and the respective pouring curves, that is to say the curves representing the tipping angle of the crucible as a function of time, are stored directly in memories. That pouring curve which produces the best pouring result is used as a model for subsequent pouring operations. The memory containing the optimum pouring curve is thus the "master" memory for all future pouring operations. The memory automatically controls the pouring operation from beginning to end and in this manner ensures its reproducibility from charge to charge.
The actual operation of pouring out the molten material generally begins only at a crucible tipping angle of approximately 30.degree. when the molten material just touches the pouring lip of the crucible burt does not yet run out. The end point of the pouring-out operation is dependent upon the apparatus and is, for example, 115.degree.. Between these two angular positions of the crucible, automatic pouring-out takes place by means of the teach-in method.